The researchers studied 107 married couples for three weeks. Each night, they measured their levels of the blood sugar glucose and asked each participant to stick pins in a voodoo doll representing his or her spouse. That indicated levels of aggression.

The researchers found that the lower the blood sugar levels, the more pins were pushed into the doll. In fact, people with the lowest scores pushed in twice as many pins as those with the highest blood sugar levels, the researchers said….

The study procedure also raised [an unusual] problem. Bushman had to handle a call from his credit card company, which wanted to make sure it was really he who had spent $5,000 to buy more than 200 voodoo dolls.

“Intimate partner violence affects millions of people globally. One possible contributing factor is poor self-control. Self-control requires energy, part of which is provided by glucose. For 21 days, glucose levels were measured in 107 married couples. To measure aggressive impulses, each evening participants stuck between 0 and 51 pins into a voodoo doll that represented their spouse, depending how angry they were with their spouse. To measure aggression, participants competed against their spouse on a 25- trial task in which the winner blasted the loser with loud noise through headphones. As expected, the lower the level of glucose in the blood, the greater number of pins participants stuck into the voodoo doll, and the higher intensity and longer duration of noise participants set for their spouse.”